java.util.NoSuchElementException: key not found

java.util.NoSuchElementException: key not found

Hi All,

I suspect I am experiencing a bug. I've noticed that while running
larger jobs, they occasionally die with the exception
"java.util.NoSuchElementException: key not found xyz", where "xyz"
denotes the ID of some particular task. I've excerpted the log from
one job that died in this way below and attached the full log for
reference.